Aquarium Substrate Calculator
Work out how much substrate fills your tank to the depth you want, including a bed that slopes up toward the back.
Your estimate will appear here
Enter the inside footprint and the depth you want. Everything runs in your browser.
How the estimate works
The calculator multiplies the inside length and width by the average depth. For a slope, the average depth is halfway between the front and back depths, which assumes an even ramp. Real beds are rarely perfectly even, and rock or wood placed on the bed takes up space, so treat the result as a starting point and round up to whole bags.
Why weight is optional
Substrates are sold by weight or by volume, and their bulk density varies widely: lightweight aquasoils weigh far less per liter than sand or gravel. Rather than guess, the calculator only shows a weight when you enter the density the manufacturer publishes. Otherwise, compare the liters figure with the volume printed on the bag.
Choosing a depth
How deep to go depends on the substrate and the plants. Our substrate guide covers the trade-offs, and the substrate buying guide compares specific products.
Other planning tools
- Aquarium volume calculator: Actual water volume from inside dimensions and water height, which is usually less than the size printed on the box.
- Plant problem checklist: Match what you see to possible explanations and the safest first checks. It narrows things down; it doesn't diagnose.
- Maintenance checklist: A routine tailored to your filter, livestock, CO2, and fertilizers: what to glance at daily, do weekly, and check every few weeks.